Answer:
The error in the given sentence is a punctuation error.
Explanation:
In the given sentence, the error is in the use of quotation marks for the name of the book. Using quotations for names of books, movies, or any title is an important factor of any correct sentence writing.
And as such, the use of this punctuation mark will enable the readers to understand what the speaker is talking about. The given sentence must be correctly written as
<u><em>"Cry, the Beloved Country" was such a good book! I've never seen the movie, though.
</em></u>
Thus, the error in the given sentence is a punctuation error.
